The present invention relates to a screen display apparatus for visually displaying a picture or a screen with a good three-dimensional effect. More particularly, the invention relates to a screen displaying apparatus for visually displaying a still picture or a motion picture with an intensive three-dimensional effect by utilizing an optical illusion of the eyes of a human being, and to a lens structure well adaptable for the screen displaying apparatus.
Development of the device and method for displaying a three-dimensional image is under progress. A holography-basis device and a device utilizing a binocular parallax of human vision have widely been known. Those devices are complicated in construction and high in cost, however. Accordingly, those devices find use in some limited places, such as amusement parks and other amusement facilities. In other works, those are not yet in widespread use.
In the circumstances, techniques have been proposed which are capable of three-dimensionally displaying a two-dimensional image, such as a normal photograph or a picture displayed on a television screen, with a relatively simple construction, viz. depending on such a complicated construction as mentioned above. Examples of those techniques are JP-A-60-59317, entitled xe2x80x9cOptical Device for Producing a Natural, Visual and Optically Interactive Image in a Free Spacexe2x80x9d, and JP-A-2000-98298, entitled xe2x80x9cStereoscopic Video Optical Devicexe2x80x9d. Each of those techniques is capable of three-dimensionally displaying the two-dimensional image and the like without the need to use the complicated construction.
xe2x80x9cOptical Devicexe2x80x9d of JP-A-60-59317 is constructed as shown in FIG. 13. First and second convex lens lenses 200 and 201, both being rectangular convex Fresnel lenses, are located between a CRT monitor 100 and a viewer E. Those components are covered with a cover 400. The viewer E views a virtual image 300, which is formed by processing an image displayed on the CRT monitor 100 by a combination of the first convex lens 200 and second convex lens 201, and can perceive a three-dimensional image.
In xe2x80x9cStereoscopic Video Optical Devicexe2x80x9d of JP-A-2000-98298, as shown in FIG. 14, a viewer sees an illusion image 301 of a subject 101 for photography, which is located within a housing 401, through a convex Fresnel lens 202, and can perceive a three-dimensional image of the subject. The technical principle of this publication is substantially the same as that of the already described publication, except that the convex Fresnel lens 202 is movable along an optical axis between the lens itself and the object 101 by means of a moving means 500. In the technique of the publication, the three-dimensional effect is more enhanced through the movement of the convex Fresnel lens 202.
A new technique of xe2x80x9cNew Stereoscopic Vision Filterxe2x80x9d is disclosed in an exhibition room established in association with xe2x80x9cThe 50th society for 3-D Video Forum (Dec. 4, 1999)xe2x80x9d. The material about the new technique distributed describes as follows:
xe2x80x9cIn the filter, a number of series of microlens elements are arrayed. In the filter, a number of series of microlens elements are arrayed. Those individual lens elements serve as pixels. Images by the lens elements are enlarged and reduced in size, but a whole image as a gathering of those lens elements is neither enlarged nor reduced. The image formed by each lens element is formed at a virtual position, and hence a whole image as a gathering of those micro-images is also formed at a virtual position. In other words, the filter is a special lens system capable of forming an image, not enlarged nor reduced, at a virtual position. As the result of forming an image at a virtual position, a two-dimensional image is viewed as a three-dimensional image, in connection with the xe2x80x9caccommodationxe2x80x9d as one of the stereoscopically perceiving functions of the eyes. This is a sort of an optical illusion of the eyes. This fact is well known as described on the magnifying glass for forming an enlarged image by Dr. Takakei Okoshi in his book xe2x80x9c3-D Image Science and Technologyxe2x80x9d. In the filter, the magnifying function of the magnifying glass is removed, and only the image position is spaced from that of the subject as in the magnifying glass. One can perceive the displayed whole image, neither enlarged nor reduced in size, viz., of its original size, in a three-dimensional fashion. The filter produces the feeling of distance as if a distant object moves to the back, not a straightforward three-dimensional feeling as if an object suddenly comes out, which is yielded on the basis of the xe2x80x9cbinocular parallaxxe2x80x9d widely used in the systems yielding the stereoscopic feeling. Accordingly, the beauty is created with a gentle stereoscopic effect. Use of the filter varies a shade of color, and the resultant image looks more beautiful. The reason why the color tone is varied is unclear; however, it is certain that the color shade variation is not due to the development of the stereoscopic feeling. The filter presented in the exhibition uses microlens that are each cylindrical in shape, and is analogous to the lenticular plate. However, the stereoscopic vision filter is different from the well known stereoscopic vision using the lenticular plate. This is readily seen from the difference between the displayed images of them. The conventional stereoscopic vision based on the lenticular plate needs a special image by composing images viewed from at least two points in a rectangular shape. On the other hand, the stereoscopic image presenting system of the filter needs a normal image viewed from one point. Accordingly, in is capable of presenting a three-dimensional image by using a normal photograph or a normal picture. The filter used in this stereoscopic image presenting system is characterized in that a focal distance of each microlens of the microlens array is considerably larger than that of the conventional lenticular plate. When considering the working technique, it is difficult to form the curved surface of the lens at the boundary surface between it and air. When the boundary surface between solids or between a solid and a liquid is used instead, the lens will easily be formed. Thus, the lens is formed in such a manner as to kill the characteristic of the lens, which has not ever been present.xe2x80x9d A micro-lens array and a display apparatus using the same, which employ the above-mentioned features are disclosed in Japanese Patent Publication 2001-42805 published on Feb. 16, 2001.
The new technique described above produces the three-dimensional effect in a manner that as in the publication of JP-A-60-59317, a virtual image or a real image is formed at a position spaced from that of the subject. However, it is different from the publication technique in that pixels are formed anew by those individual microlenses.
It is certain that the filter yields the xe2x80x9cthree-dimensional effectxe2x80x9d. However, there is no exact theoretical explanation of the reason why the technique yields the three-dimensional effect. At the present stage, the reason for this is commonly explained by a xe2x80x9cpsychological explanation xe2x80x9cthe yielding of the three-dimensional effect will be due to the optical illusion of the eyes of the human beingxe2x80x9d. Granting that the xe2x80x9coptical illusion theoryxe2x80x9d is correct, some people delve into the xe2x80x9coptical illusion theoryxe2x80x9d and will (physiologically) explain it in the terms of the structure of the brain of the human being (especially visual area) or an outside-world recognizing method of the brain (as it were, data processing method of the brain). However, this approach is still uncertain in its reliability. In any case, however, it is a proven fact that the above-mentioned means gives the human being (his eyes) a three-dimensional feeling, and the reproducibility of this fact is confirmed.
The conventional techniques mentioned above suffers from the following problems. The devices utilizing the holography a binocular parallax of human vision need extremely complicated constructions, as already described. With regard to the optical-illusion basis devices, viz., the devices of JP-A-60-59317 and JP-A-2000-98298, the former needs provision of a couple of lenses, and the latter needs provision of the moving means 500. Further, the cover 400 or the housing 401 is indispensably used for both the techniques. As a consequence, the devices are bulky in size, complicated in construction and high in cost. Special shortcoming is that the three-dimensional effect produced by the techniques of JP-A-60-59317 and JP-A-2000-98298 and other techniques based on the former techniques are still unsatisfactory.
A display device, which is different in principle from the techniques of the above-mentioned publications, is disclosed in Japanese Patent No. 3022558. In the disclosed display device, two-dimensional pictures are displayed on a plurality of display surfaces whose depth positions are different from one another. An observer simultaneously views those images to perceive a three-dimensional picture. To present a three-dimensional picture, this display device needs a plurality of two dimensional images prepared in accordance with the specifications. In other words, it is impossible to produce a three-dimensional image from one two-dimensional image. The stereoscopic vision filter, which was presented in an exhibition room established in association with xe2x80x9cThe 50th society for the Study of 3-D Video Forum (Dec. 4, 1999)xe2x80x9d, succeeds in device size reduction, but still suffers from the problem of insufficient three-dimensional effect.
Accordingly, an object of the present invention is to provide a screen display apparatus which visually presents a three-dimensional picture which gives a viewer an intensive three-dimensional feeling, with simple construction and at low cost, and a lens structure well adaptable for such a screen display apparatus.
To achieve the above object, according to a first aspect of the invention, there is provided a screen display apparatus which is capable of visually presenting a virtual image and/or a real image of a subject to a viewer at a position, which is different from a position of the subject, the virtual image and/or the real image being vertically inclined with respect to the viewer, and The upper part of the virtual image and/or the real image being located farther than the lower part thereof from the viewer.
According to a second aspect of the invention, a screen display apparatus is characterized in that an inclination angle of the virtual image and/or the real image is within a range of 3xc2x0 to 40xc2x0 with respect to a right confronting plane. A third screen display apparatus is characterized in that a part of the virtual image and/or the real image intersects a part of the subject. A fourth screen display apparatus is characterized in that the subject is substantially equal in size to the virtual image and/or the real image. A fifth screen display apparatus is characterized in that the virtual image and/or the real image is made flat.
A sixth screen display apparatus is characterized in that the virtual image and/or the real image is formed through an action of a microlens array consisting of a plurality of microlenses or a lenticular lens.
A seventh screen display apparatus is characterized in that a pitch at which the plurality of microlenses are arrayed is 300 xcexcm or shorter. An eighth screen display apparatus is characterized in that the virtual image and/or the real image is slanted by, making the focal distances of the plurality of microlenses different. A ninth screen display apparatus is characterized in that when the subject is an image displayed on a CRT or an LCD screen, a pitch at which pixels are arrayed on the CRT or LCD screen is equal to the lens pitch of the plurality of microlenses arrayed.
A tenth screen display apparatus is characterized in that the subject is a two-dimensional image.
In the invention, a first lens structure consists of a microlens array consisting of convex and concave microlenses, which are alternately arrayed, or a lenticular lens, and is capable of visually presenting a virtual image and/or a real image of a subject to a viewer at a position different from a position of the subject in a state that the virtual image and/or the real image is inclined such that an upper part of the virtual image and/or the real image is located farther than a lower part thereof from the viewer.
An eleventh screen display apparatus of the present invention is a screen display apparatus formed with a primary image of a subject and a lens plate including a plurality of microlenses and being located the primary image and a viewer, wherein the lens plate forms a plurality of secondary images being differently distanced from the viewer and enables the viewer to perceive the plurality of secondary images as a single image.
A twelfth screen display apparatus is characterized in that assuming that Lx is a distance from the viewer to pixels forming one of the plurality of secondary images, and Ly is a distance from the viewer to pixels forming another secondary image, when Lx greater than Ly, the following expression is satisfied
Lxxe2x88x92Lyxe2x89xa70.05xc2x7Ly.
A thirteenth screen display apparatus is characterized in that assuming that Lx is a distance from the viewer to pixels forming one of the plurality of secondary images, and Ly is a distance from the viewer to pixels forming another secondary image, when Lx greater than Ly, the following expression is satisfied
0.5xc2x7Lyxe2x89xa7Lxxe2x88x92Ly.
A fourteenth screen display apparatus is characterized in that a maximum value of the lens pitch of the plurality of microlenses arrayed is 500 xcexcm or shorter.
A fifteenth screen display apparatus is characterized in that the lens plate includes a portion where the plurality of microlenses are formed and another portion having no lens action.
A sixteenth screen display apparatus is characterized in that the plurality of microlenses are convex and concave microlenses.
A seventeenth screen display apparatus is characterized in that distances from the viewer to the plurality of secondary images are different for each the microlens.